BIT 1988 Volume 7 Issue 1

This research examined how off-angle or oblique viewing of a VDU screen and
the physical location of a message on the screen influenced message legibility.
Eight trained subjects viewed five-character long common words, number strings,
and alphanumeric messages presented at 15 different combinations of oblique
viewing angle and location of message on the VDU screen for 2.5 seconds. It
was found that common words and number strings showed little overall loss in
legibility except when oblique viewing angle exceeded ±32°.
Alphanumeric messages were found to have a significantly lower legibility than
the common words and number strings. It was recommended that for best overall
legibility of the three types of messages studied here, that oblique viewing
angles be less than ±32°. Predictor equations were also developed
to aid in predicting loss of accuracy based on the type of message and physical
features of the viewing task.

Readers of documents on CRT displays report difficulties in remembering
whereabouts in a lengthy text they previously read something. Four experiments
explore whether subdividing such texts, at appropriate thematic boundaries,
into five successive coloured sections can aid readers' retrieval of
information. Experiment 1, using texts presented on coloured paper, showed
that this use of colour helped readers relocate information. Experiment 2
presented the same texts on a CRT, but variation in the colour of the
characters on the screen did not help readers relocate information. Experiment
3 replicated the findings of experiment 2, with texts differing in both content
and structure from those used previously. Experiment 4, again using coloured
text on a CRT display, showed that giving readers a visible guide to the
ordering of the coloured sections was not sufficient to restore the advantage
that coloured pages had for texts presented on paper. The implications of
these findings for variation in the background and foreground colouring of
multi-window displays are discussed, but the main conclusion concerns the
caution needed when transferring information design solutions across media.

A pilot study was undertaken to assess the efficacy of selected graph types
and information coding schemes in producing quick and accurate graph
interpretation. Point-plots, line graphs, bar graphs, and three-dimensional
bar graphs were constructed and displayed using an IBM-PC microcomputer with
colour monitor. The effectiveness of each of these graph types, as well as the
coding scheme used within each (colour versus monochrome), was investigated
using 32 subjects in four separate experiments involving either point-reading,
point-comparison, trend-reading, or trend-comparison tasks. Dependent measures
including task completion time, graph interpretation error, subjective mental
workload rating, and graph preference rating were obtained. In three of the
tasks, colour-coded graphs were associated with lower task completion time,
lower rated mental workload, and higher rated preference than monochrome
graphs. However, there were no differences in subjects' error scores between
colour and monochrome coding for any of the tasks. For the point-reading task,
the three-dimensional bar graphs were less effective than the other graph
types, though there were no differences among graph types for the other three
tasks. Implications for graph design given specific data interpretation tasks
are discussed, based on the results of the four experiments and related
literature.

The Effect of Tree Structure on Search in a Hierarchical Menu Selection
System

Search processes in a hierarchical menu selection system were investigated
in a study that varied the structure of the tree. A hierarchical data base was
composed of 256 gift items grouped into different clusters and presented using
menus. Depth of the tree was held constant while breadth varied with level.
Five structures were explored with the following number of alternatives at each
of four levels: constant (4 x 4 x 4 x 4), decreasing (8 x 8 x 2 x 2),
increasing (2 x 2 x 8 x 8), concave (8 x 2 x 2 x 8), and convex (2 x 8 x 8 x
2). Subjects searched for either specifically named gifts (explicit targets)
or gifts appropriate for a scenario situation (scenario targets). In general,
explicit targets took less time to find and fewer frames to traverse than for
scenario targets. For explicit targets, the increasing menu was slightly
superior to the rest. Search time was about the same across the five tree
structures for explicit targets, but differed greatly for scenario targets.
The concave and increasing structures were faster than the constant structure
and the convex and decreasing structures were slower. Similar results were
found for the number of frames traversed. The patterns of search also differed
greatly among the five structures in terms of the frequency of use of the
'previous' command and the 'top' command. The 'previous' command was used most
frequently with the convex menu and least frequently with the concave menu.
For scenario targets, the 'top' command was used most frequently with the
decreasing menu and least frequently with the increasing menu. For explicit
targets, the 'top' command was used most frequently with concave menu and least
frequently with increasing menu. The pattern of search indicated that if
subjects moved back up the tree they tended to move to a level with eight
choices rather than two. Overall, it is concluded that the concave menu is
superior when searching for scenario targets and the increasing menu is
slightly superior when searching for explicit targets. A theory of menu
uncertainly based on information theory is proposed which helps to account for
some of the results.

Monitoring computer users' behaviour to enhance the usability of software
has become increasingly popular among the developers of computer products. One
objective of this paper is to compare the use of a software monitoring
technique with other field observation methods. It is argued that when
contrasted against traditional observation techniques, the software monitor
provides a more accurate and unobtrusive approach to collecting behavioural
data on larger samples of individuals for longer periods of time than either
participant observation or Thinking Aloud methodologies. A second objective is
to demonstrate the application of software monitors on installed multi-user
systems. Technical aspects of software monitor design and discussed, with
emphasis on specific practical problems in monitor design and utilization when
making the transition from the laboratory to an office environment. Data from
two studies are presented. The first illustrates how a software monitor can be
used to determine the impact and acceptance of various software packages in an
integrated office automation product. The second study examines how software
monitor data were used to modify the interface to a specific electronic mail
facility.

This questionnaire study reports results on some aspects of COM -- a
computer-mediated communication system. It was found that the main reasons for
starting to use the COM system were the need for information, curiosity and use
as a complement to the telephone. The greatest benefits were being able to
obtain information and opinions and to spread information. The COM
communication was judged to be dominated by users with a good ability to
communicate in writing. The subjects expressed a wish for a chairman who could
organize the conference discussions. They experienced spontaneity in COM, but
to a certain extent also misunderstandings and aggression. COM was generally
seen as easy, friendly and stimulating. The general conclusion is that COM was
thought of as an efficient tool for sending and receiving information which
does not involve complex communication.

BIT 1988 Volume 7 Issue 2

The knowledge elicitation problem arises from the need to acquire the
knowledge of human experts in an explicit form suitable for encoding in a
computer program such as an expert system. This is very difficult to perform
successfully because of the size and complexity of knowledge structures in the
human brain, and because much procedural knowledge is tacit and unavailable to
conscious verbal report via interview methods. The present paper draws upon an
extensive review of research in the field of cognitive psychology in an attempt
to offer a practical approach to this problem. First, a wide range of
cognitive theories concerning the nature of knowledge representation in humans
is considered, and a synthesis of the current state of theory is provided.
Second, attention is drawn to a number of performance factors which may
constrain the exhibition of a person's underlying cognitive competence. There
then follows a review and discussion of a number of alternative psychological
methodologies that might be applied to the elicitation of different types of
human knowledge. Finally, some suggestions are made for the application of the
psychological work discussed to the practical problem of knowledge elicitation.

Information retrieval involves the balance of two mnemonic processes:
recognition of items presented to the user, and recall of where wanted
documents might be. Iconic methods of human-computer interaction are seen to
assist the recognition processes by virtue of the enrichment of cues provided.
However, the principle of cue enrichment could apply equally to the process of
recall, which is arguably a process more needing of support. This paper
reports two exploratory experiments using icons to support the recall process
in information retrieval. The results indicate no exceptional levels of
recall. However, some aspects of users' performance suggest icons used in this
way have some interesting and exploitable mnemonic properties. In particular,
they may be useful in enhancing and supporting the search process by rapidly
limiting the number of documents through which a user might be asked to search.

Expert-Novice Knowledge Organization: An Empirical Investigation Using
Computer Program Recall

Expertise in a given domain is regarded as being manifested in the knowledge
structures or chunks that experts possess. This research sought to use the
chunking hypothesis of expertise, operationalized via computer program recall,
to distinguish the more expert from the less expert computer programmers in a
group of programming professionals. Two expertise levels were required to
investigate differences in debugging processes of expert and novice
programmers. The programmer classification produced by the recall pretest,
however, explained little variation in debug time and the number of errors
subjects made, when compared with a programmer classification based on the
effectiveness of subjects' chunking processes.
Subjects' recalled programs were examined to determine whether the
information structures in the program used for recall matched the declarative
knowledge structures programmers could be expected to possess. Examination of
the program suggests that programmers may not have been expected to possess two
of the knowledge structures represented in the program. Examination of the
programmers' recalled programs suggests that those programmers classified as
experts by the process classification may have had greater difficulty in
recalling this program than those classified as novices, leading to the
hypothesis that experts may be affected more than novices by non-matching
knowledge structures.

An Empirical Comparison of Menu Selection, Command Entry and Combined Modes
of Computer Control

Command entry and menu selection control modes, along with a combination of
the two, were compared using objective performance and subjective preference
measures. Experienced as well as novice users of an interactive computer aided
design system participated in the study. Although command entry produced
performance that was superior to the other two modes, there was a strong user
preference for the combined mode. Therefore, it is recommended that combined
modes of control be considered for future systems, as long as there is a means
to deactivate the menus. These results dispel the notion that menus are
necessarily viewed as a hindrance by experienced users of a computer system.

In a teletext service, where pages of information are retrieved from a
random sequence of pages broadcast cyclically on a video channel, the mean and
variance of system response times are directly related to the number of pages
in the cycle. Previous experiments have shown that viewers express annoyance
with delays in system response, and that the frequency of such expressions
increases non-linearly with delay. This paper examines possible explanations
for the reported annoyance. A first experiment investigated the effect on
annoyance of different kinds of feedback to the viewer following a page
request. Results showed that annoyance grew at a slower rate when continuous,
rhythmic feedback was present. Further, knowledge of the actual duration of
the delay had no effect on viewers' annoyance. A second experiment showed that
the same continuous feedback shortened viewers' estimates of the durations of
the delays. These results suggest that annoyance is due to the experienced
delay in system response time, and not to mere awareness of the duration.

The design of most automated equipment is guided primarily by technical and
economic considerations. The social science aspects of the system, if
considered at all, are usually confined to the important questions of work
organization, or man-machine interface design, or both. Social scientists are
rarely given the opportunity to participate in the design of the often complex
details of the actual technology that lies behind the man-machine interface.
This paper gives consideration to the social shaping of computer numerically
controlled lathe technology, which implies that social, technical and economic
considerations are used in the design of the technology. The characteristics
of a decision support system, which was designed jointly by engineers and
social scientists with the aim of allowing the existing skills of machinists to
evolve into new skills in relation to the changed technology, are described.
The implications for the role and values of system designers that this system
implies are also discussed.

The Interaction between the Use of Information Technology and Organizational
Culture

The interaction between the use of information technology, (IT) in
organizations and that organization's culture is examined. The interaction is
considered from the early stages of specification through to the regular use of
the systems. The changes in the technological artifacts which result from the
use of IT are discussed. Some suggestions about control of the interaction are
made.

BIT 1988 Volume 7 Issue 3

Several studies have demonstrated performance benefits associated with
self-defined computer commands (aliases). This study further investigated the
possibility of empirically establishing pools of self-generated (idiographic)
command names for novice (nomothetic) use by others. Experiment 1 showed that
when given the commands and functions from which they were derived, independent
expert (E) and novice (N) groups were able to discriminate between bona fide
and bogus aliases at above chance levels, despite surface heterogeneity,
although Es were more able to do this than Ns. Experiment 2 compared the
understandability of E and N created aliases for independent groups of Es and
Ns. Results showed that E aliases were more understandable than N aliases and
that Es understood all aliases better. That is, Es exhibited a decoding
advantage (due to experience) and an advantage in encoding semantic content in
their aliases. In Experiment 3 Rosenberg's 'command suggestiveness' index
showed that the mean suggestiveness of E aliases was significantly higher than
that of N aliases. Moreover, for experiments 1 and 2, subjects' confidence in
matching aliases to their parent functions was significantly correlated with
suggestiveness. To test the utility of the suggestiveness metric, lists of
high, medium and low suggestiveness aliases were constructed and subjects
learned all lists in counterbalanced order. Recall using command functions as
cues showed that more of the higher suggestiveness aliases were remembered. It
was concluded that despite aliases surface heterogeneity, they possess
sufficient semantic content to allow identification of their original
functions. Moreover, Es produce more meaningful aliases and experiment 4
revealed that this may be due to greater suggestiveness. Generalizing from
these findings, it appears appropriate that for complex systems where novice
understanding is limited, performance may be facilitated by establishing E
alias pools from which the most efficacious are empirically selected using the
methods proposed by Rosenberg.

Callers' Perceptions of Post-Dialling Delays: The Effects of a New
Signalling Technology

The present paper reports an investigation of the potential impact of
introducing common-channel signalling (CCS) into the current telephone network.
This technology would have the effect of greatly diminishing post-dialling
delay (PDD). As such, its main benefits would be obtained by introducing it
into the toll network, in which PDDs are much longer than in the local network.
The issues examined concerned potential 'contrast' effects, in that reducing
PDDs in the toll network may cause callers to be less patient with normal PDDs
in the local network. Three laboratory studies were undertaken to evaluate
caller impatience and abandonment under (1) the current system, (2) the current
local system with a simulated new toll system and (3) the current toll system
with a simulated new local system. Ratings of impatience and abandonment
increased on local calls when the new technology was implemented on the toll
network, but not vice versa. The explanation offered is based on a 'cognitive'
contrast effect resulting from callers' expectations that toll PDDs should
always be longer than local PDDs. The implications of this effect for caller
behaviour with the introduction of CCS are discussed. Any negative effects on
local call behaviour are outweighed by the much shorter PDDs on the toll
network and should be counteracted by the gradual introduction of CCS.

Hierarchical Planning as Method for Task Analysis: The Example of Office
Task Analysis

The paradigm of hierarchical planning from artificial intelligence
literature is used to describe 133 office tasks. Various levels of abstraction
are described. Their number varies with the tasks. From several examples we
demonstrate that some of these levels can be grouped and that any task can be
broken down using a four-level model: the most abstract level of the task
formulation; the expert level, which represents specific context procedures (or
subtasks); the highest common level, these being common procedures which are
domain independent; the lowest verbalizable level, or elementary actions. Then
the common procedures are considered as possible functions in a computer aided
system. From a detailed analysis of some of these common procedures, we
emphasize the obligatory or optional features of certain actions. Using an
example we propose a function description which takes these features into
account.

The Effects of an Active Development of the Mental Model in the Training
Process: Experimental Results in a Word Processing System

Three different training programmes for a word processing system were
experimentally compared: (1) a sequential programme, which taught low-level
skills and which did not help the user actively to develop a mental model, (2)
a hierarchical programme, which provided an explicit and integrated conceptual
model of the system to the user and (3) a programme in which the users were
asked to develop hypotheses on the functioning of the software and in which
they were encouraged to use an active and exploratory approach. From an action
theory point of view it was hypothesized that the third group would be superior
to the first group. In an experimental study with two training sessions each
of two hours and a two-hour testing session (n=15), this was shown to be the
case for several performance criteria (error time, transfer and experimenter
rating). Additionally, an interindividual difference variable to measure the
individual learning style was used, giving results that could be interpreted in
a similar way to the experimental results.

Service industries are an increasingly important part of most developed
economies as employers of displaced manufacturing labour. Computers are
currently used in fewer than 30% of British service organizations and it has
been suggested that this low level of utilization is attributable to cost. A
study of managers in the largest service industry in the United Kingdom, the
hospitality industry, shows that it is not cost attitudes but management
attitudes which are the major inhibitory factor. Furthermore, these findings
are consistent with other studies of attitudes to computers of senior managers
in British industry. A comparison with a study of the attitudes of some
American professional persons suggests that this is not necessarily
attributable simply to educational level. In such circumstances it seems
probable that penetration levels will increase slowly and that creative
applications of computers in service industries, which may reduce their
propensity to absorb labour, are not imminent.

The Contributions of Cognitive Engineering to the Design and Use of Expert
Systems

The cognitive basis of several issues critical to building expert systems is
reviewed. Required and desirable attributes of a knowledge elicitation
methodology are identified. It is argued that knowledge should be elicited
from several levels of expertise. Plausible contributions of research in human
problem solving to knowledge representation and design of control structure are
examined. Implications of the literature on human learning and on
expert-novice differences for machine learning are reviewed. The applicability
of systems, which rely on user modelling, to the design of intelligent
interfaces is discussed.

BIT 1988 Volume 7 Issue 4

Organizational adjustment to technological change and its impact upon human
resources should be based on an understanding of employee perceptions and
behavioural responses to such developments. An analytic framework which
relates strategic choice to internal labour market and employee determinism is
derived from the methods employed by organizational theorists and psychologists
to generate a set of typologies. The framework divides variables in four
classes: (1) natural selection, with minimum choice and adaptation or selection
out; (2) differentiation, with high choice and high employee determinism and
adaptation within constraints; (3) strategic choice, with maximum choice and
adaptation by design; and (4) undifferentiated choice, with incremental choice
and adaptation by chance. Useful in reconciling previously inconsistent or
incompatible theories of technological change, the framework is offered as a
co-ordination device to integrate the results of divergent approaches to
technological adaptation studies.

Two electronic mail systems were studied within an organization: an
executive system for upper management and a general system for all employees.
The results from 130 interviews indicated that both systems were perceived to
contribute to productivity, a reduction in use of memos and a reduction in
telephone calls. However, the executive system was perceived to be more
satisfactory and more effective than the general system. The ratio of positive
comments to negative comments was used as an independent measure of
satisfaction with each electronic mail system. The user comments were also
classified and discussed in terms of types of perceived advantages and problems
with these systems.

A Cognitively Based Methodology for Evaluating Human Performance in the
Computer-Aided Design Task Domain

This article describes a methodology for evaluating human performance in the
computer aided design (CAD) task environment. The methodology is based
primarily on cognitive theoretic frameworks that are consistent with processes
presumed to underlie human design activities. The motivation for its
development stems from rapid software and hardware advances in CAD systems and
our relative lack of understanding of how these enhancements affect human
design performance for (1) fundamentally different types of tasks and (2)
different levels of complexity for a particular task. This methodology is
currently being applied to computer aided architectural design, an area where
artificial intelligence (AI), enhanced geometric modelling and other system
features are being debated in terms of their usefulness in aiding the human's
design activities.

The introduction of robots into any organization forms part of a
considerable investment in new technology over a range of applications in the
search for efficiency and increased productivity. The greater consistency and
quality associated with robot operations compared with that of the human
operator, is regarded as an advantage both in relation to the manufacturing
process and to the product. However, in order to make the most efficient use
of robots, the ability to generate good robot programs must be developed.
Traditional robot programming techniques are extremely slow and laborious.
Off-line programming by textual input alone is an equally tedious process. In
this paper, existing and potential problems associated with off-line
programming are examined. Various commercial and experimental robot languages
and their relative important features are described. Opinions of manufacturers
of CNC (Computer Numerically Controlled) machines and robots concerning both
user interfaces and potential candidate users are discussed. Both the training
and the abilities of the candidate robot programmers are important aspects of
any robot programming system, although obviously much will depend on the
sophistication of the particular application. Recommendations are made
concerning issues that should be taken into account when developing future
off-line programming systems.

Human Intelligence Models and Their Implications for Expert System Structure
and Research

In order to determine the features which contribute to intelligent
behaviour, several models of human intelligence were studied. This evaluation
identified ten features present in human intelligent behaviour which may be
relevant to expert systems design. These features were rated, by experts in
the field of expert systems, on the extent of their presence in expert systems
as compared with intelligent human behaviour. The four features receiving the
lowest ratings were social competence, comprehension, automatization and memory
management. The paper concludes with a discussion of these four features and
outlines what needs to be done and why in order to incorporate them into the
structure of expert systems.

What We Know and What We Need to Know: The User Model versus the User's
Model in Human-Computer Interaction

An argument is made for the importance of studying the real, as opposed to
idealized, behaviour of the computer user. Formal methods which model user
behaviour in terms of production rules are criticized because they fail to
account for the unique behaviour which results either from problems arising in
the normal work routine, or from novices who create their own patterns of
interaction with the machine. This latter point is illustrated with reference
to a study of novice users. How well are such users able to identify the
knowledge they need when learning how to use a new system, and what kinds of
knowledge of the system do they seek? It seems that in the absence of a
suitable, generalizable model of a word processing system, these users
structure their own learning experience badly, making poor use of the little
experience they have. The behaviour of such users deviates markedly from that
of the 'ideal user' captured within formal task descriptions.

The Concept of an Information Management System and its Use within Design
Studies

This paper describes the concept of an information management system (IMS)
and its association with a user centered approach to the design of equipment
which acts as a medium for the user to attain a goal. The case is taken where
such mediating devices (MDs) involve computer based processing, storage and
communications arrangements, and transactions with either a physical
environment or engineered facilities. Particular attention is drawn to the
designer's role in defining the data transformations within an MD, and hence to
information that is available to the user and the means of carrying out
transactions with it, transforming it into knowledge and attaining a goal.
There is also special emphasis on the usability (= operability + trainability)
aspects of the user's interface with the MD. The means of exploring design
options are described along with the possible assessment techniques. It is
concluded that the concept of an IMS offers considerable benefits for studying
a range of design issues and matters of scientific importance.

This paper is concerned with how to provide easy and effective access to
computer databases containing pictures rather than text. Experiences with
several types of graphic material suggested that hierarchical menu indexes were
unlikely to be effective. What seemed to be required was a probabilistic
method which could tolerate a certain amount of error and uncertainty. As a
solution, we propose a feature matching approach in which users describe what
they want to retrieve. Descriptions are elicited by a set of queries. The
system then matches user descriptions with descriptions of items in the
database, and responds with the best fitting items.
Initial tests suggest that this type of system may have the qualities we
were looking for. First, it appears to tolerate errors, in that the user's
description may disagree with the database's in a number of ways and still lead
to the correct item. Second, it permits uncertainty, in that the user can
choose the non-committal response of 'maybe' without the retrieval process
coming to a halt. Third, it appears to require no training or manuals, only a
few brief instructions on screen. It therefore seems well suited to the
non-expert user.

Two experiments are reported which compared proof-reading performance in
various VDU display formats. Experiment 1 found that displaying text one
paragraph at a time improved the accuracy of performance, relative to a full
screen condition, but at the expense of speed. Subject also preferred using
the paragraph format. Display contrast (positive vs negative) had no effect on
performance. Experiment 2 supported the findings of Experiment 1, and found
increased accuracy when text was further subdivided into sentences, but speed
was again reduced. Possible explanations for the format effect are presented,
and its practical implications are considered.